A semiconductor circuit element mounted (loaded) on a circuit board generates heat according to the operation of an electronic device. Therefore, in order to efficiently discharge the heat, a heat sink (a heat exchange component) is mounted (fixed) to the circuit board to be compression-bonded (closely attached) to the semiconductor circuit element. According to the improvement of performance of the semiconductor circuit element, the circuit board is further increased in density. Concerning the heat sink, there is increasing necessity to enable a high-performance heat sink to be quickly and accurately fixed in a small attaching area.
Incidentally, when a heat sink 1′ is mounted (fixed) on a circuit board B, for example, as shown in FIG. 17, mounting means employing a wire spring 41′ having a substantially Z shape in plan view is known (see, for example, Patent Literature 1).
In this method, components (anchors 5′) having a substantially U shape for hooking both ends of the wire spring 41′ are set on the circuit board B in advance. To press the heat sink 1′ with the wire spring 41′, both end portions of the wire spring 41′ are hooked to (fit in) U-shape portions of the anchors 5′ while being bent. The heat sink 1′ is pressed and fixed to the circuit board B side.
As the anchors 5′, there are the anchors 5′ fit in and set from the opposite side of a mounting surface of the heat sink 1′ (the substrate rear surface) as shown in an enlarged view of FIG. 17(a) and the anchors 5′ set on the mounting surface side of the heat sink 1′ (the upper surface of the circuit board B) as shown in FIG. 17(b). In the case of FIG. 17(a) in which the anchors 5′ are set from the substrate rear surface, brim-like flanges 53′ are formed to prevent the anchors 5′ from slipping off the circuit board B with a tensile force of the wire spring 41′. On the other hand, in the case of FIG. 17(b) in which the anchors 5′ are set from the substrate upper surface, portions projecting to the substrate rear surface need to be fixed by solder or the like.
The anchors 5′ having the substantially U shape have a problem explained below. In FIG. 17(a), elongated holes (slit-like openings) have to be formed on the circuit board B in order to fit the anchors 5′ therein. In FIG. 17(b), elongated ranges on the substrate have to be secured as areas for attachment in order to attach the anchors 5′ (slit-like areas). Therefore, in both cases, as a result, a relatively large range including the elongated areas on the circuit board B cannot be used for a circuit.
Various members other than the heat sink 1′ (the semiconductor circuit element) are mounted on the circuit board B. Further, in general, the anchors 5′ are arranged in two places on the outer side of the heat sink 1′ (further on the outer side than a range in which the heat sink 1′ is mounted) and on a diagonal line because of a structure in which both tips of the wire spring 41′ are hooked to the anchors 5′. Therefore, an effective area of the circuit board B tends to further decrease. Consequently, although the areas are secured to set the anchors 5′, the increase in the areas that cannot be used as a circuit is a significant factor of influence and limitation on circuit design.
Further, for example, work for forming the slit-like openings shown in FIG. 17(a) on the circuit board B is difficult work compared with work for opening circular holes. There is also room of improvement concerning labor and time required for machining (work).